Existing document capture devices generally fall into two categories: camera based (referred to as document cameras) and line scan based (referred to as document scanners).
Document cameras use Charge-Coupled Device (CCD)- or Complementary Metal-Oxide Semiconductor (CMOS)-type image sensors, and the appropriate optics, to take a picture of the document and store the image in memory. From there, the image is compressed and converted to a standard graphics format before being transferred to a local computer. Although document cameras are fast, they are also bulky and expensive. Document cameras also have a relatively low resolution.
Document scanners use a linear array of CCDs (or light-emitting diodes and photodiodes), along with special optics and an electro-mechanical system to capture an image of the document one line at a time. Similar to document cameras, a document scanner performs image compression and conversion to a standard graphics format on the image data after it is captured. Document scanners are less expensive than document cameras, but they are slower and bulkier. Also, the images provided by document scanners are generally of poorer quality than document cameras.